<template>
    <div class="pagination">
    <button :disabled="pageNo==1" @click="$emit('getPageNo', pageNo-1)" :class="{active:pageNo==1}">上一页</button>
    <button v-if="startNumAndEndNum.start>1" @click="$emit('getPageNo', 1)">1</button> 
    <button v-if="startNumAndEndNum.start>2">···</button>

    <button v-for="(page,index) in startNumAndEndNum.end" :key="index" v-if="page>startNumAndEndNum.start" @click="$emit('getPageNo', page)" :class="{active:pageNo==page}">{{page}}</button>
    
    
    <button v-if="startNumAndEndNum.end<totalPage-1">···</button>
    <button v-if="startNumAndEndNum.end<totalPage" @click="$emit('getPageNo', totalPage)" :class="{active:pageNo==totalPage}">{{totalPage}}</button>
    <button :disabled="pageNo==totalPage">下一页</button>
    
    <button style="margin-left: 30px">{{total}}</button>
  </div>
</template>

<script>
export default {
    name:'Pagination',
    props:['pageNo','pageSize','total','continues'],
    computed:{
        totalPage(){
            return Math.ceil(this.total/this.pageSize)
        },
        startNumAndEndNum(){
            const {continues,totalPage,pageNo} = this;
            let start = 0 , end = 0;

            if(continues>total){
                start = 1;
                 end = totalPage
            }else{
                start = pageNo - parseInt(continues/2)
                end = pageNo + parseInt(continues/2)
                if(start<1){
                    start = 1;
                    end = continues
                }
                if(end>totalPage){
                    end = totalPage;
                    start = totalPage - continues + 1; 
                }
            }
            return {start,end}
        }
    }

}
</script>

<style lang="less" scoped>
  .pagination {
    text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
  .active{
    background: skyblue;
  }
</style>